The present invention relates to an apparatus and method for use in handling sheet material and more specifically to an apparatus and method for feeding sheet material articles from a hopper.
Known apparatus for feeding sheet material articles is disclosed in U.S. Pat. Nos. 3,650,525 and 3,702,187. This apparatus includes a hopper which supports a stack of sheet material articles. A separator is engageable with a front edge portion of a sheet material article to pull the sheet material article downwardly toward a pickup location. A feed drum has a plurality of spaced apart grippers which sequentially grip sheet material articles at the pickup location. The feed drum pulls the sheet material articles from the hopper and moves the sheet material articles to receiving locations on a conveyor disposed beneath the feed drum.
In an apparatus of the type disclosed in the aforementioned patents, the grippers on a feed drum are disposed at equally spaced increments along the periphery of the feed drum. The distance between adjacent grippers is sufficient to support a sheet material article throughout the length of the sheet material article. In addition, there is sufficient distance between the rear or trailing edge portion of a first sheet material article and the front or leading edge portion of a next succeeding sheet material article to allow the separator to move the front edge portion of the second sheet material article to the pickup location during rotation of the feed drum after feeding of the first sheet material article from the hopper.
For example, when twelve inch long sheets are to be fed from a hopper, the distance along the surface of the feed drum between adjacent grippers may be eighteen inches. This eighteen inches includes twelve inches for engagement with the side surface of a sheet material article. The additional six inches of drum circumference is required to enable the separator to engage and move a front edge portion of the next succeeding sheet material article to the pickup location.
The distance which must be provided along the circumference of the drum to enable the separator to move a front edge portion of a sheet material article to the pickup location decreases the extent of the peripheral surface of the drum which is available for engagement with the sheet material article. Therefore, the maximum length of the sheet material article which can be handled by a particular feed drum is a function of both the diameter of the drum and the time required for the separator to engage and move the front edge portion of a sheet material article to a pickup location.